Currently, a bendable or foldable module, i.e., a flexible module, has been developed, and it is of a multiple-layer structure. For example, a flexible display panel designed on the basis of an electroluminescent structure usually includes such layers as a back film, a pixel control circuit, an electroluminescent pixel element, a barrier film (BF), a circular polarizer (C-POL), a touch element and a hard coat (HC) one on top of the other. Generally, the entire module has a thickness of 200 to 600 μm.
In the case that the flexible module and a mechanical structure for support and fixation are assembled into a machine, the mechanical structure may be fully attached and fixed to the flexible module, so the thickness of the flexible module may increase indirectly, and a position of a neutral layer of the flexible module may change (during a bending procedure of a material, an outer layer of the material may be stretched, an inner layer thereof may be squeezed, and there will inevitably exist on a cross section of the material a transition layer which is not stretched nor squeezed, i.e., a stress applied thereto is almost zero; this transition layer is called as the neutral layer of the material). On one hand, a larger bending force needs to be applied so as to bend the machine. On the other hand, the layers of the flexible module may easily be separated from each other, so a normal display effect may be adversely affected.